vous savez que g(x) = -2x = -2 * x
donc que g(-1/2) = -2 * (-1/2) = +1
et si g(x) = -20
alors - 2 * x = -20 => x = -20 / (-2) = 10
=> g(10)= - 20
vous trouvez aussi x pour que g(x) = 10
et
h(x) = 1/4x = 1/4 * x
si x = 1/4 => h(1/4) = 1/4 * 1/4 = 1/16
si x = 8 => h(8) = 1/4 * 8 = ...
et si h(x) = 3/4
alors 1/4 * x = 3/4
donc x = 3/4 / (1/4) = 3/4 * 4 = 3
